Flexible Carrier Aggregation with Deactivated Secondary Cell Downlink
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Solution Overview
Problem
Current 5G wireless systems face limitations in carrier aggregation configurations, particularly when the number of uplink carriers is fewer than downlink carriers, leading to issues like overlapping frequency bands and unpredictable user equipment behavior during handovers, as existing standards require both uplink and downlink for primary cells and optional uplink for secondary cells, restricting flexible UL/DL assignments.
Innovation Solution
The proposed solution involves configuring user equipment to operate in carrier aggregation with a primary cell and secondary cells by deactivating downlink for the secondary cell, allowing simultaneous transmission on two uplink bands and reception on multiple bands, using dynamic radio resource control configurations and time division multiplexing patterns to manage overlapping frequencies and enable flexible UL/DL usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If downlink is activated for secondary cell in carrier aggregation, then downlink communication capability is improved, but uplink carrier resources are consumed and interference increases when uplink carriers are fewer than downlink carriers
Solution Approach 1:
The patent applies dynamics by making the downlink activation state of the secondary cell configurable and changeable based on network conditions. The network can dynamically switch between activating and deactivating downlink for the secondary cell through RRC configuration, allowing the system to adapt to varying traffic patterns and interference conditions, thus resolving the contradiction between maintaining downlink capability and reducing interference.
Solution Approach 2:
The patent changes the parameter of downlink activation state for the secondary cell from a fixed state to a configurable state. By introducing the parameter 'dl-Deactivation' in the RRC configuration that can be set to true or false, the system can adjust the downlink activation status based on the number of available uplink carriers, thereby controlling interference while maintaining necessary downlink communication capability.
2Productivity
If flexible UL/DL assignments are implemented in carrier aggregation, then network performance is improved, but device complexity increases
Solution Approach 1:
The patent implements universality by designing a unified RRC configuration structure that handles both traditional and flexible UL/DL assignments. The configuration message can universally apply to different carrier aggregation scenarios (with or without flexible assignments) using the same message format and processing logic, thereby improving network performance while avoiding additional device complexity through standardized multi-functional configuration.
3Productivity
If overlapping frequency bands are used for uplink transmission, then spectral efficiency is improved, but interference and unpredictable UE behavior increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring the flexible UL/DL assignment parameters in the RRC message before the actual carrier aggregation operation. The network provides advance notice to the UE about which secondary cells have flexible assignments and what the specific configurations are, allowing the UE to prepare appropriate handover behaviors in advance, thus maintaining spectral efficiency while ensuring predictable handover behavior.
Data Source
AI summary
Systems, methods, apparatuses, and computer program products for configuring a user equipment to operate in carrier aggregation in a serving cell with a primary cell and one or more secondary cell are provided. For example, a method can include receiving, from a primary cell, a carrier aggregation configuration of a secondary cell with uplink. The configuration indicates that downlink is deactivated for the secondary cell. The carrier aggregation configuration is applicable to carrier aggregation of the primary cell and the secondary cell. The method also includes communicating with the secondary cell based on the configuration of the secondary cell.